Treat hidden API exemptions as whitelist.

Update docs accordingly.

Test: m
Bug: 64382372
Merged-In: Ief8daf3badeb046b0461a3ebcd289e242d559070
Change-Id: Ief8daf3badeb046b0461a3ebcd289e242d559070
(cherry picked from commit 33d5138e132561d6c3c02fc0e265aa3c158f6798)
1 file changed